Keyscan CA250B, Technical Instructions

Page: 80 / 140

Keyscan Inc. – Technical Guide (PC109x - 04.15) 80
Power-up & Test Voltages
Power Supply Specifications
The DPS-15 power supply for CA & EC control boards is a dual power supply with two (2) linear DC outputs.
Each output is rated at 12 VDC – 1.2 Amperes.
Before making any power connections at the ACU, Keyscan recommends that you use the following two tables
and calculate the sum of the current demand for the devices drawing power from the ACU supply side and the
RDR AUX supply side ensuring that you do not exceed the DPS-15’s current capacity.
On CA8500B control boards, readers with higher current specifications may collectively exceed the capacity of
the DPS-15 RDR AUX supply. If this occurs, you require an additional power supply.
Do not connect the reader power wire (red) to the ACU supply side of the DPS-15.
Wiring Connections
Before connecting power at the ACU, be sure to observe the following points:
 verify the devices do not exceed the power supply ratings
 check the cable and wire connections
 ensure no short circuits exist when measuring voltages
 verify the DC polarity is correct for all equipment
 ensure backup battery is fully charged
Following the above guidelines ensures each device will function properly and not be damaged.
DPS-15 Dual Power Supply – Current Calculation
The DPS-15 power supply has two independent linear 1.2 Amp DC outputs – the ACU supply and the AUX RDR
supply. Use the following two tables for calculating the total current required from the ACU supply and the AUX
RDR supply. Please note the ACU supply and the AUX RDR supply each have an operational limit of 1000 mA.
ACU Supply – 1.2 A
Opposite Add-on Board #, enter the name of the module in the Product Description column and the board’s
current requirement in the Current Rating column. All Keyscan circuit board current ratings are listed near the
back of the technical guide on page 135. Current ratings are also labeled on the circuit boards. Add all the
current ratings including the control board to determine the total current. Keyscan recommends a 200 mA
reserve operating margin. The total current from the ACU supply, including the control board, should not
exceed 1000 mA.